Differential round trip time based positioning

ABSTRACT

Disclosed are techniques for determining a position of a user equipment (UE). A differential round-trip-time (RTT) based positioning procedure is proposed to determine the UE position. In this technique, the UE position is determined based on the differences of the RTTs between the UE and a plurality of base stations. The differential RTT based positioning procedure has much looser inter-gNodeB timing synchronization requirements than the OTDOA technique and also has much looser group delay requirements than traditional RTT procedures.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application for Patent claims priority under 35 U.S.C. § 119to Greek Patent Application No. 20180100562, entitled “DIFFERENTIALROUND TRIP TIME BASED POSITIONING,” filed Dec. 19, 2018, assigned to theassignee hereof, and expressly incorporated herein by reference in itsentirety.

TECHNICAL FIELD

Various aspects described herein generally relate to wirelesscommunication systems, and more particularly, to differential round triptime (RTT) based positioning.

BACKGROUND

Wireless communication systems have developed through variousgenerations, including a first-generation analog wireless phone service(1G), a second-generation (2G) digital wireless phone service (includinginterim 2.5G and 2.75G networks), a third-generation (3G) high speeddata, Internet-capable wireless service, and a fourth-generation (4G)service (e.g., Long Term Evolution (LTE) or WiMax). There are presentlymany different types of wireless communication systems in use, includingcellular and personal communications service (PCS) systems. Examples ofknown cellular systems include the cellular analog advanced mobile phonesystem (AMPS), and digital cellular systems based on code divisionmultiple access (CDMA), frequency division multiple access (FDMA), timedivision multiple access (TDMA), the Global System for Mobile access(GSM) variation of TDMA, etc.

A fifth generation (5G) mobile standard, referred to as “New Radio”(NR), calls for higher data transfer speeds, greater numbers ofconnections, and better coverage, among other improvements. The 5Gstandard, according to the Next Generation Mobile Networks Alliance, isdesigned to provide data rates of several tens of megabits per second toeach of tens of thousands of users, with 1 gigabit per second to tens ofworkers on an office floor. Several hundreds of thousands ofsimultaneous connections should be supported in order to support largesensor deployments. Consequently, the spectral efficiency of 5G mobilecommunications should be significantly enhanced compared to the current4G standard. Furthermore, signaling efficiencies should be enhanced andlatency should be substantially reduced compared to current standards.

Some wireless communication networks, such as 5G, support operation atvery high and even extremely-high frequency (EHF) bands, such asmillimeter wave (mmW) frequency bands (generally, wavelengths of 1 mm to10 mm, or 30 to 300 GHz). These extremely high frequencies may supportvery high throughput such as up to six gigabits per second (Gbps).

To support position estimations in terrestrial wireless networks, amobile device can be configured to measure and report the observed timedifference of arrival (OTDOA) or reference signal timing difference(RSTD) between reference RF signals received from two or more networknodes (e.g., different base stations or different transmission points(e.g., antennas) belonging to the same base station). The mobile devicecan also be configured to report the time of arrival (ToA) of RFsignals.

With OTDOA, when the mobile device reports the time difference ofarrival (TDOA) between RF signals from two network nodes, the locationof the mobile device is then known to lie on a hyperbola with thelocations of the two network nodes as the foci. Measuring TDOAs betweenmultiple pairs of network nodes allows for solving the for mobiledevice's position as intersections of the hyperbolas.

Round trip time (RTT) is another technique for determining a position ofa mobile device. RTT is a two-way messaging technique (network node tomobile device and mobile device to network node), with both the mobiledevice and the network node reporting their receive-to-transmit (Rx-Tx)time differences to a positioning entity, such as a location server orlocation management function (LMF), that computes the mobile device'sposition. This allows for computing the back-and-forth flight timebetween the mobile device and the network node. The location of themobile device is then known to lie on a circle (for two-dimensionalpositioning) or a sphere (for three-dimensional positioning) with acenter at the network node's position. Reporting RTTs with multiplenetwork nodes allows the positioning entity to solve for the mobiledevice's position as the intersection of the circles or spheres.

SUMMARY

This summary identifies features of some example aspects, and is not anexclusive or exhaustive description of the disclosed subject matter.Whether features or aspects are included in, or omitted from thissummary is not intended as indicative of relative importance of suchfeatures. Additional features and aspects are described, and will becomeapparent to persons skilled in the art upon reading the followingdetailed description and viewing the drawings that form a part thereof.

An exemplary method performed by a network node is disclosed. The methodcomprises collecting a plurality of RTTs between a user equipment (UE)and a plurality of base stations (BSs). Each RTT of the plurality ofRTTs is associated with a BS of the plurality of BSs. Also, each RTTrepresents a total flight time of an RTT signal back and forth betweenthe UE and the associated BS. The method also comprises performing adifferential RTT based positioning procedure to determine a position ofthe UE based on differences of the RTTs among the plurality of RTTs.

An exemplary method performed by a wireless device is disclosed. Themethod comprises providing one or more group delay parameters for thewireless device to a positioning entity. The one or more group delayparameters may comprise an RTT type parameter indicating whether RTTsreported by the wireless device are measured RTTs or actual RTTs. It maybe determined that a group delay of the wireless device is included inthe reported RTTs when the RTT type parameter indicates that thereported RTTs are measured RTTs.

An exemplary network node is disclosed. The network node comprises atleast one transceiver, at least one memory component, and at least oneprocessor. The at least one transceiver, the at least one memorycomponent, and the at least one processor are configured to collect aplurality of RTTs between a UE and a plurality of BSs. Each RTT of theplurality of RTTs is associated with a BS of the plurality of BSs. Also,each RTT represents a total flight time of an RTT signal back and forthbetween the UE and the associated BS. The at least one transceiver, theat least one memory component, and the at least one processor are alsoconfigured to perform a differential RTT based positioning procedure todetermine a position of the UE based on differences of the RTTs amongthe plurality of RTTs.

An exemplary wireless device is disclosed. The wireless node comprisesat least one transceiver, at least one memory component, and at leastone processor. The at least one transceiver, the at least one memorycomponent, and the at least one processor are configured to provide oneor more group delay parameters for the wireless device to a positioningentity. The one or more group delay parameters may comprise an RTT typeparameter indicating whether RTTs reported by the wireless device aremeasured RTTs or actual RTTs. It may be determined that a group delay ofthe wireless device is included in the reported RTTs when the RTT typeparameter indicates that the reported RTTs are measured RTTs.

Another exemplary network node is disclosed. The network node comprisesmeans for collecting a plurality of RTTs between a UE and a plurality ofBSs. Each RTT of the plurality of RTTs is associated with a BS of theplurality of BSs. Also, each RTT represents a total flight time of anRTT signal back and forth between the UE and the associated BS. Thenetwork node also comprises means for performing a differential RTTbased positioning procedure to determine a position of the UE based ondifferences of the RTTs among the plurality of RTTs.

Another exemplary wireless device is disclosed. The wireless devicecomprises means for providing one or more group delay parameters for thewireless device to a positioning entity. The one or more group delayparameters may comprise an RTT type parameter indicating whether RTTsreported by the wireless device are measured RTTs or actual RTTs. It maybe determined that a group delay of the wireless device is included inthe reported RTTs when the RTT type parameter indicates that thereported RTTs are measured RTTs.

An exemplary non-transitory computer-readable medium storingcomputer-executable instructions for a network node is disclosed. Thecomputer-executable instructions comprise one or more instructionscausing the network node to collect a plurality of RTTs between a UE anda plurality of BSs. Each RTT of the plurality of RTTs is associated witha BS of the plurality of BSs. Also, each RTT represents a total flighttime of an RTT signal back and forth between the UE and the associatedBS. The computer-executable instructions also comprise one or moreinstructions causing the network node to perform a differential RTTbased positioning procedure to determine a position of the UE based ondifferences of the RTTs among the plurality of RTTs.

An exemplary non-transitory computer-readable medium storingcomputer-executable instructions for a wireless device is disclosed. Thecomputer-executable instructions comprise one or more instructionscausing the wireless device to provide one or more group delayparameters for the wireless device to a positioning entity. The one ormore group delay parameters may comprise an RTT type parameterindicating whether RTTs reported by the wireless device are measuredRTTs or actual RTTs. It may be determined that a group delay of thewireless device is included in the reported RTTs when the RTT typeparameter indicates that the reported RTTs are measured RTTs.

Other objects and advantages associated with the aspects disclosedherein will be apparent to those skilled in the art based on theaccompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofexamples of one or more aspects of the disclosed subject matter and areprovided solely for illustration of the examples and not limitationthereof:

FIG. 1 illustrates a high-level system architecture of a wirelesscommunications system in accordance with an aspect of the disclosure;

FIGS. 2A and 2B illustrate example wireless network structures,according to various aspects;

FIGS. 3A to 3C are simplified block diagrams of several sample aspectsof components that may be employed in wireless communication nodes andconfigured to support communication as taught herein;

FIG. 4 illustrates an exemplary technique for determining a position ofa UE.

FIG. 5A illustrates a scenario for determining RTT between a transmitterand a receiver, and FIG. 5B is a diagram showing exemplary timingswithin an RTT occurring in the scenario of FIG. 5A during a wirelessprobe request and a response;

FIG. 6 illustrates an exemplary method performed by a network node todetermine a UE position according to an aspect of the disclosure;

FIG. 7 illustrates an exemplary process performed by a network node todetermine a UE position through absolute RTT based positioning accordingto an aspect of the disclosure;

FIG. 8 illustrates an exemplary process performed by a network node todetermine a UE position through differential RTT based positioningaccording to an aspect of the disclosure;

FIG. 9 illustrates an exemplary method performed by a UE to determine aUE position according to an aspect of the disclosure; and

DETAILED DESCRIPTION

Aspects of the subject matter are provided in the following descriptionand related drawings directed to specific examples of the disclosedsubject matter. Alternates may be devised without departing from thescope of the disclosed subject matter. Additionally, well-known elementswill not be described in detail or will be omitted so as not to obscurethe relevant details.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects. Likewise, the term “aspects” does not require that allaspects include the discussed feature, advantage, or mode of operation.

The terminology used herein describes particular aspects only and shouldnot be construed to limit any aspects disclosed herein. As used herein,the singular forms “a,” “an,” and “the” are intended to include theplural forms as well, unless the context clearly indicates otherwise.Those skilled in the art will further understand that the terms“comprises,” “comprising,” “includes,” and/or “including,” as usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Further, various aspects may be described in terms of sequences ofactions to be performed by, for example, elements of a computing device.Those skilled in the art will recognize that various actions describedherein can be performed by specific circuits (e.g., an applicationspecific integrated circuit (ASIC)), by program instructions beingexecuted by one or more processors, or by a combination of both.Additionally, these sequences of actions described herein can beconsidered to be embodied entirely within any form of non-transitorycomputer-readable medium having stored thereon a corresponding set ofcomputer instructions that upon execution would cause an associatedprocessor to perform the functionality described herein. Thus, thevarious aspects described herein may be embodied in a number ofdifferent forms, all of which have been contemplated to be within thescope of the claimed subject matter. In addition, for each of theaspects described herein, the corresponding form of any such aspects maybe described herein as, for example, “logic configured to” and/or otherstructural components configured to perform the described action.

As used herein, the terms “user equipment” (UE) and “base station” arenot intended to be specific or otherwise limited to any particular RadioAccess Technology (RAT), unless otherwise noted. In general, a UE may beany wireless communication device (e.g., a mobile phone, router, tabletcomputer, laptop computer, tracking device, wearable (e.g., smartwatch,glasses, augmented reality (AR)/virtual reality (VR) headset, etc.),vehicle (e.g., automobile, motorcycle, bicycle, etc.), Internet ofThings (IoT) device, etc.) used by a user to communicate over a wirelesscommunications network. A UE may be mobile or may (e.g., at certaintimes) be stationary, and may communicate with a Radio Access Network(RAN). As used herein, the term “UE” may be referred to interchangeablyas an “access terminal” or “AT,” a “client device,” a “wireless device,”a “subscriber device,” a “subscriber terminal,” a “subscriber station,”a “user terminal” or UT, a “mobile terminal,” a “mobile station,” orvariations thereof. Generally, UEs can communicate with a core networkvia a RAN, and through the core network the UEs can be connected withexternal networks such as the Internet and with other UEs. Of course,other mechanisms of connecting to the core network and/or the Internetare also possible for the UEs, such as over wired access networks,wireless local area network (WLAN) networks (e.g., based on IEEE 802.11,etc.) and so on.

A base station may operate according to one of several RATs incommunication with UEs depending on the network in which it is deployed,and may be alternatively referred to as an access point (AP), a networknode, a NodeB, an evolved NodeB (eNB), a New Radio (NR) Node B (alsoreferred to as a gNB or gNodeB), etc. In addition, in some systems abase station may provide purely edge node signaling functions while inother systems it may provide additional control and/or networkmanagement functions. A communication link through which UEs can sendsignals to a base station is called an uplink (UL) channel (e.g., areverse traffic channel, a reverse control channel, an access channel,etc.). A communication link through which the base station can sendsignals to UEs is called a downlink (DL) or forward link channel (e.g.,a paging channel, a control channel, a broadcast channel, a forwardtraffic channel, etc.). As used herein the term traffic channel (TCH)can refer to either an UL/reverse or DL/forward traffic channel.

The term “base station” may refer to a single physicaltransmission-reception point (TRP) or to multiple physical TRPs that mayor may not be co-located. For example, where the term “base station”refers to a single physical TRP, the physical TRP may be an antenna ofthe base station corresponding to a cell of the base station. Where theterm “base station” refers to multiple co-located physical TRPs, thephysical TRPs may be an array of antennas (e.g., as in a multiple-inputmultiple-output (MIMO) system or where the base station employsbeamforming) of the base station. Where the term “base station” refersto multiple non-co-located physical TRPs, the physical TRPs may be adistributed antenna system (DAS) (a network of spatially separatedantennas connected to a common source via a transport medium) or aremote radio head (RRH) (a remote base station connected to a servingbase station). Alternatively, the non-co-located physical TRPs may bethe serving base station receiving the measurement report from the UEand a neighbor base station whose reference RF signals the UE ismeasuring. Because a TRP is the point from which a base stationtransmits and receives wireless signals, as used herein, references totransmission from or reception at a base station are to be understood asreferring to a particular TRP of the base station.

An “RF signal” comprises an electromagnetic wave of a given frequencythat transports information through the space between a transmitter anda receiver. As used herein, a transmitter may transmit a single “RFsignal” or multiple “RF signals” to a receiver. However, the receivermay receive multiple “RF signals” corresponding to each transmitted RFsignal due to the propagation characteristics of RF signals throughmultipath channels. The same transmitted RF signal on different pathsbetween the transmitter and receiver may be referred to as a “multipath”RF signal.

According to various aspects, FIG. 1 illustrates an exemplary wirelesscommunications system 100. The wireless communications system 100 (whichmay also be referred to as a wireless wide area network (WWAN)) mayinclude various base stations 102 and various UEs 104. The base stations102 may include macro cell base stations (high power cellular basestations) and/or small cell base stations (low power cellular basestations). In an aspect, the macro cell base station may include eNBswhere the wireless communications system 100 corresponds to an LTEnetwork, or gNBs where the wireless communications system 100corresponds to a NR network, or a combination of both, and the smallcell base stations may include femtocells, picocells, microcells, etc.

The base stations 102 may collectively form a RAN and interface with acore network 170 (e.g., an evolved packet core (EPC) or next generationcore (NGC)) through backhaul links 122, and through the core network 170to one or more location servers 172. In addition to other functions, thebase stations 102 may perform functions that relate to one or more oftransferring user data, radio channel ciphering and deciphering,integrity protection, header compression, mobility control functions(e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, RAN sharing, multimedia broadcast multicast service(MBMS), subscriber and equipment trace, RAN information management(RIM), paging, positioning, and delivery of warning messages. The basestations 102 may communicate with each other directly or indirectly(e.g., through the EPC/NGC) over backhaul links 134, which may be wiredor wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. In an aspect, one or more cellsmay be supported by a base station 102 in each coverage area 110. A“cell” is a logical communication entity used for communication with abase station (e.g., over some frequency resource, referred to as acarrier frequency, component carrier, carrier, band, or the like), andmay be associated with an identifier (e.g., a physical cell identifier(PCID), a virtual cell identifier (VCID)) for distinguishing cellsoperating via the same or a different carrier frequency. In some cases,different cells may be configured according to different protocol types(e.g., machine-type communication (MTC), narrowband IoT (NB-IoT),enhanced mobile broadband (eMBB), or others) that may provide access fordifferent types of UEs. Because a cell is supported by a specific basestation, the term “cell” may refer to either or both the logicalcommunication entity and the base station that supports it, depending onthe context. In some cases, the term “cell” may also refer to ageographic coverage area of a base station (e.g., a sector), insofar asa carrier frequency can be detected and used for communication withinsome portion of geographic coverage areas 110.

While neighboring macro cell base station 102 geographic coverage areas110 may partially overlap (e.g., in a handover region), some of thegeographic coverage areas 110 may be substantially overlapped by alarger geographic coverage area 110. For example, a small cell basestation 102′ may have a coverage area 110′ that substantially overlapswith the coverage area 110 of one or more macro cell base stations 102.A network that includes both small cell and macro cell base stations maybe known as a heterogeneous network. A heterogeneous network may alsoinclude home eNBs (HeNBs), which may provide service to a restrictedgroup known as a closed subscriber group (CSG).

The communication links 120 between the base stations 102 and the UEs104 may include UL (also referred to as reverse link) transmissions froma UE 104 to a base station 102 and/or downlink (DL) (also referred to asforward link) transmissions from a base station 102 to a UE 104. Thecommunication links 120 may use MIMO antenna technology, includingspatial multiplexing, beamforming, and/or transmit diversity. Thecommunication links 120 may be through one or more carrier frequencies.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or less carriers may be allocated for DL than for UL).

The wireless communications system 100 may further include a wirelesslocal area network (WLAN) access point (AP) 150 in communication withWLAN stations (STAs) 152 via communication links 154 in an unlicensedfrequency spectrum (e.g., 5 GHz). When communicating in an unlicensedfrequency spectrum, the WLAN STAs 152 and/or the WLAN AP 150 may performa clear channel assessment (CCA) or listen before talk (LBT) procedureprior to communicating in order to determine whether the channel isavailable.

The small cell base station 102′ may operate in a licensed and/or anunlicensed frequency spectrum. When operating in an unlicensed frequencyspectrum, the small cell base station 102′ may employ LTE or NRtechnology and use the same 5 GHz unlicensed frequency spectrum as usedby the WLAN AP 150. The small cell base station 102′, employing LTE/5Gin an unlicensed frequency spectrum, may boost coverage to and/orincrease capacity of the access network. NR in unlicensed spectrum maybe referred to as NR-U. LTE in an unlicensed spectrum may be referred toas LTE-U, licensed assisted access (LAA), or MulteFire.

The wireless communications system 100 may further include a millimeterwave (mmW) base station 180 that may operate in mmW frequencies and/ornear mmW frequencies in communication with a UE 182. Extremely highfrequency (EHF) is part of the RF in the electromagnetic spectrum. EHFhas a range of 30 GHz to 300 GHz and a wavelength between 1 millimeterand 10 millimeters. Radio waves in this band may be referred to as amillimeter wave. Near mmW may extend down to a frequency of 3 GHz with awavelength of 100 millimeters. The super high frequency (SHF) bandextends between 3 GHz and 30 GHz, also referred to as centimeter wave.

Communications using the mmW/near mmW radio frequency band have highpath loss and a relatively short range. The mmW base station 180 and theUE 182 may utilize beamforming (transmit and/or receive) over a mmWcommunication link 184 to compensate for the extremely high path lossand short range. Further, it will be appreciated that in alternativeconfigurations, one or more base stations 102 may also transmit usingmmW or near mmW and beamforming. Accordingly, it will be appreciatedthat the foregoing illustrations are merely examples and should not beconstrued to limit the various aspects disclosed herein.

Transmit beamforming is a technique for focusing an RF signal in aspecific direction. Traditionally, when a network node (e.g., a basestation) broadcasts an RF signal, it broadcasts the signal in alldirections (omni-directionally). With transmit beamforming, the networknode determines where a given target device (e.g., a UE) is located(relative to the transmitting network node) and projects a strongerdownlink RF signal in that specific direction, thereby providing afaster (in terms of data rate) and stronger RF signal for the receivingdevice(s). To change the directionality of the RF signal whentransmitting, a network node can control the phase and relativeamplitude of the RF signal at each of the one or more transmitters thatare broadcasting the RF signal. For example, a network node may use anarray of antennas (referred to as a “phased array” or an “antennaarray”) that creates a beam of RF waves that can be “steered” to pointin different directions, without actually moving the antennas.Specifically, the RF current from the transmitter is fed to theindividual antennas with the correct phase relationship so that theradio waves from the separate antennas add together to increase theradiation in a desired direction, while cancelling to suppress radiationin undesired directions.

Transmit beams may be quasi-collocated, meaning that they appear to thereceiver (e.g., a UE) as having the same parameters, regardless ofwhether or not the transmitting antennas of the network node themselvesare physically collocated. In NR, there are four types ofquasi-collocation (QCL) relations. Specifically, a QCL relation of agiven type means that certain parameters about a second reference RFsignal on a second beam can be derived from information about a sourcereference RF signal on a source beam. Thus, if the source reference RFsignal is QCL Type A, the receiver can use the source reference RFsignal to estimate the Doppler shift, Doppler spread, average delay, anddelay spread of a second reference RF signal transmitted on the samechannel. If the source reference RF signal is QCL Type B, the receivercan use the source reference RF signal to estimate the Doppler shift andDoppler spread of a second reference RF signal transmitted on the samechannel. If the source reference RF signal is QCL Type C, the receivercan use the source reference RF signal to estimate the Doppler shift andaverage delay of a second reference RF signal transmitted on the samechannel. If the source reference RF signal is QCL Type D, the receivercan use the source reference RF signal to estimate the spatial receiveparameter of a second reference RF signal transmitted on the samechannel.

In receive beamforming, the receiver uses a receive beam to amplify RFsignals detected on a given channel. For example, the receiver canincrease the gain setting and/or adjust the phase setting of an array ofantennas in a particular direction to amplify (e.g., to increase thegain level of) the RF signals received from that direction. Thus, when areceiver is said to beamform in a certain direction, it means the beamgain in that direction is high relative to the beam gain along otherdirections, or the beam gain in that direction is the highest comparedto the beam gain in that direction of all other receive beams availableto the receiver. This results in a stronger received signal strength(e.g., reference signal received power (RSRP), reference signal receivedquality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) ofthe RF signals received from that direction.

Receive beams may be spatially related. A spatial relation means thatparameters for a transmit beam for a second reference signal can bederived from information about a receive beam for a first referencesignal. For example, a UE may use a particular receive beam to receive areference downlink reference signal (e.g., synchronization signal block(SSB)) from a base station. The UE can then form a transmit beam forsending an uplink reference signal (e.g., sounding reference signal(SRS)) to that base station based on the parameters of the receive beam.

Note that a “downlink” beam may be either a transmit beam or a receivebeam, depending on the entity forming it. For example, if a base stationis forming the downlink beam to transmit a reference signal to a UE, thedownlink beam is a transmit beam. If the UE is forming the downlinkbeam, however, it is a receive beam to receive the downlink referencesignal. Similarly, an “uplink” beam may be either a transmit beam or areceive beam, depending on the entity forming it. For example, if a basestation is forming the uplink beam, it is an uplink receive beam, and ifa UE is forming the uplink beam, it is an uplink transmit beam.

In 5G, the frequency spectrum in which wireless nodes (e.g., basestations 102/180, UEs 104/182) operate is divided into multiplefrequency ranges, FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). In amulti-carrier system, such as 5G, one of the carrier frequencies isreferred to as the “primary carrier” or “anchor carrier” or “primaryserving cell” or “PCell,” and the remaining carrier frequencies arereferred to as “secondary carriers” or “secondary serving cells” or“SCells.” In carrier aggregation, the anchor carrier is the carrieroperating on the primary frequency (e.g., FR1) utilized by a UE 104/182and the cell in which the UE 104/182 either performs the initial radioresource control (RRC) connection establishment procedure or initiatesthe RRC connection re-establishment procedure. The primary carriercarries all common and UE-specific control channels, and may be acarrier in a licensed frequency (however, this is not always the case).A secondary carrier is a carrier operating on a second frequency (e.g.,FR2) that may be configured once the RRC connection is establishedbetween the UE 104 and the anchor carrier and that may be used toprovide additional radio resources. In some cases, the secondary carriermay be a carrier in an unlicensed frequency. The secondary carrier maycontain only necessary signaling information and signals, for example,those that are UE-specific may not be present in the secondary carrier,since both primary uplink and downlink carriers are typicallyUE-specific. This means that different UEs 104/182 in a cell may havedifferent downlink primary carriers. The same is true for the uplinkprimary carriers. The network is able to change the primary carrier ofany UE 104/182 at any time. This is done, for example, to balance theload on different carriers. Because a “serving cell” (whether a PCell oran SCell) corresponds to a carrier frequency/component carrier overwhich some base station is communicating, the term “cell,” “servingcell,” “component carrier,” “carrier frequency,” and the like can beused interchangeably.

For example, still referring to FIG. 1, one of the frequencies utilizedby the macro cell base stations 102 may be an anchor carrier (or“PCell”) and other frequencies utilized by the macro cell base stations102 and/or the mmW base station 180 may be secondary carriers(“SCells”). The simultaneous transmission and/or reception of multiplecarriers enables the UE 104/182 to significantly increase its datatransmission and/or reception rates. For example, two 20 MHz aggregatedcarriers in a multi-carrier system would theoretically lead to atwo-fold increase in data rate (i.e., 40 MHz), compared to that attainedby a single 20 MHz carrier.

The wireless communications system 100 may further include one or moreUEs, such as UE 190, that connects indirectly to one or morecommunication networks via one or more device-to-device (D2D)peer-to-peer (P2P) links. In the example of FIG. 1, UE 190 has a D2D P2Plink 192 with one of the UEs 104 connected to one of the base stations102 (e.g., through which UE 190 may indirectly obtain cellularconnectivity) and a D2D P2P link 194 with WLAN STA 152 connected to theWLAN AP 150 (through which UE 190 may indirectly obtain WLAN-basedInternet connectivity). In an example, the D2D P2P links 192 and 194 maybe supported with any well-known D2D RAT, such as LTE Direct (LTE-D),WiFi Direct (WiFi-D), Bluetooth®, and so on.

The wireless communications system 100 may further include a UE 164 thatmay communicate with a macro cell base station 102 over a communicationlink 120 and/or the mmW base station 180 over a mmW communication link184. For example, the macro cell base station 102 may support a PCelland one or more SCells for the UE 164 and the mmW base station 180 maysupport one or more SCells for the UE 164.

According to various aspects, FIG. 2A illustrates an example wirelessnetwork structure 200. For example, an NGC 210 (also referred to as a“5GC”) can be viewed functionally as control plane functions 214 (e.g.,UE registration, authentication, network access, gateway selection,etc.) and user plane functions 212, (e.g., UE gateway function, accessto data networks, IP routing, etc.) which operate cooperatively to formthe core network. User plane interface (NG-U) 213 and control planeinterface (NG-C) 215 connect the gNB 222 to the NGC 210 and specificallyto the control plane functions 214 and user plane functions 212. In anadditional configuration, an eNB 224 may also be connected to the NGC210 via NG-C 215 to the control plane functions 214 and NG-U 213 to userplane functions 212. Further, eNB 224 may directly communicate with gNB222 via a backhaul connection 223. In some configurations, the New RAN220 may only have one or more gNBs 222, while other configurationsinclude one or more of both eNBs 224 and gNBs 222. Either gNB 222 or eNB224 may communicate with UEs 204 (e.g., any of the UEs depicted in FIG.1). Another optional aspect may include location server 230, which maybe in communication with the NGC 210 to provide location assistance forUEs 204. The location server 230 can be implemented as a plurality ofseparate servers (e.g., physically separate servers, different softwaremodules on a single server, different software modules spread acrossmultiple physical servers, etc.), or alternately may each correspond toa single server. The location server 230 can be configured to supportone or more location services for UEs 204 that can connect to thelocation server 230 via the core network, NGC 210, and/or via theInternet (not illustrated). Further, the location server 230 may beintegrated into a component of the core network, or alternatively may beexternal to the core network.

According to various aspects, FIG. 2B illustrates another examplewireless network structure 250. For example, an NGC 260 (also referredto as a “5GC”) can be viewed functionally as control plane functions,provided by an access and mobility management function (AMF)/user planefunction (UPF) 264, and user plane functions, provided by a sessionmanagement function (SMF) 262, which operate cooperatively to form thecore network (i.e., NGC 260). User plane interface 263 and control planeinterface 265 connect the eNB 224 to the NGC 260 and specifically to SMF262 and AMF/UPF 264, respectively. In an additional configuration, a gNB222 may also be connected to the NGC 260 via control plane interface 265to AMF/UPF 264 and user plane interface 263 to SMF 262. Further, eNB 224may directly communicate with gNB 222 via the backhaul connection 223,with or without gNB direct connectivity to the NGC 260. In someconfigurations, the New RAN 220 may only have one or more gNBs 222,while other configurations include one or more of both eNBs 224 and gNBs222. Either gNB 222 or eNB 224 may communicate with UEs 204 (e.g., anyof the UEs depicted in FIG. 1). The base stations of the New RAN 220communicate with the AMF-side of the AMF/UPF 264 over the N2 interfaceand the UPF-side of the AMF/UPF 264 over the N3 interface.

The functions of the AMF include registration management, connectionmanagement, reachability management, mobility management, lawfulinterception, transport for session management (SM) messages between theUE 204 and the SMF 262, transparent proxy services for routing SMmessages, access authentication and access authorization, transport forshort message service (SMS) messages between the UE 204 and the shortmessage service function (SMSF) (not shown), and security anchorfunctionality (SEAF). The AMF also interacts with the authenticationserver function (AUSF) (not shown) and the UE 204, and receives theintermediate key that was established as a result of the UE 204authentication process. In the case of authentication based on a UMTS(universal mobile telecommunications system) subscriber identity module(USIM), the AMF retrieves the security material from the AUSF. Thefunctions of the AMF also include security context management (SCM). TheSCM receives a key from the SEAF that it uses to derive access-networkspecific keys. The functionality of the AMF also includes locationservices management for regulatory services, transport for locationservices messages between the UE 204 and the location managementfunction (LMF) 270, as well as between the New RAN 220 and the LMF 270,evolved packet system (EPS) bearer identifier allocation forinterworking with the EPS, and UE 204 mobility event notification. Inaddition, the AMF also supports functionalities for non-3GPP accessnetworks.

Functions of the UPF include acting as an anchor point forintra-/inter-RAT mobility (when applicable), acting as an externalprotocol data unit (PDU) session point of interconnect to the datanetwork (not shown), providing packet routing and forwarding, packetinspection, user plane policy rule enforcement (e.g., gating,redirection, traffic steering), lawful interception (user planecollection), traffic usage reporting, quality of service (QoS) handlingfor the user plane (e.g., UL/DL rate enforcement, reflective QoS markingin the DL), UL traffic verification (service data flow (SDF) to QoS flowmapping), transport level packet marking in the UL and DL, DL packetbuffering and DL data notification triggering, and sending andforwarding of one or more “end markers” to the source RAN node.

The functions of the SMF 262 include session management, UE Internetprotocol (IP) address allocation and management, selection and controlof user plane functions, configuration of traffic steering at the UPF toroute traffic to the proper destination, control of part of policyenforcement and QoS, and downlink data notification. The interface overwhich the SMF 262 communicates with the AMF-side of the AMF/UPF 264 isreferred to as the N11 interface.

Another optional aspect may include a LMF 270, which may be incommunication with the NGC 260 to provide location assistance for UEs204. The LMF 270 can be implemented as a plurality of separate servers(e.g., physically separate servers, different software modules on asingle server, different software modules spread across multiplephysical servers, etc.), or alternately may each correspond to a singleserver. The LMF 270 can be configured to support one or more locationservices for UEs 204 that can connect to the LMF 270 via the corenetwork, NGC 260, and/or via the Internet (not illustrated).

FIGS. 3A, 3B, and 3C illustrate several sample components (representedby corresponding blocks) that may be incorporated into a UE 302 (whichmay correspond to any of the UEs described herein), a base station 304(which may correspond to any of the base stations described herein), anda network entity 306 (which may correspond to or embody any of thenetwork functions described herein, including the location server 230and the LMF 270) to support the file transmission operations as taughtherein. It will be appreciated that these components may be implementedin different types of apparatuses in different implementations (e.g., inan ASIC, in a system-on-chip (SoC), etc.). The illustrated componentsmay also be incorporated into other apparatuses in a communicationsystem. For example, other apparatuses in a system may includecomponents similar to those described to provide similar functionality.Also, a given apparatus may contain one or more of the components. Forexample, an apparatus may include multiple transceiver components thatenable the apparatus to operate on multiple carriers and/or communicatevia different technologies.

The UE 302 and the base station 304 each include wireless wide areanetwork (WWAN) transceiver 310 and 350, respectively, configured tocommunicate via one or more wireless communication networks (not shown),such as an NR network, an LTE network, a GSM network, and/or the like.The WWAN transceivers 310 and 350 may be connected to one or moreantennas 316 and 356, respectively, for communicating with other networknodes, such as other UEs, access points, base stations (e.g., eNBs,gNBs), etc., via at least one designated RAT (e.g., NR, LTE, GSM, etc.)over a wireless communication medium of interest (e.g., some set oftime/frequency resources in a particular frequency spectrum). The WWANtransceivers 310 and 350 may be variously configured for transmittingand encoding signals 318 and 358 (e.g., messages, indications,information, and so on), respectively, and, conversely, for receivingand decoding signals 318 and 358 (e.g., messages, indications,information, pilots, and so on), respectively, in accordance with thedesignated RAT. Specifically, the transceivers 310 and 350 include oneor more transmitters 314 and 354, respectively, for transmitting andencoding signals 318 and 358, respectively, and one or more receivers312 and 352, respectively, for receiving and decoding signals 318 and358, respectively.

The UE 302 and the base station 304 also include, at least in somecases, wireless local area network (WLAN) transceivers 320 and 360,respectively. The WLAN transceivers 320 and 360 may be connected to oneor more antennas 326 and 366, respectively, for communicating with othernetwork nodes, such as other UEs, access points, base stations, etc.,via at least one designated RAT (e.g., WiFi, LTE-D, Bluetooth®, etc.)over a wireless communication medium of interest. The WLAN transceivers320 and 360 may be variously configured for transmitting and encodingsignals 328 and 368 (e.g., messages, indications, information, and soon), respectively, and, conversely, for receiving and decoding signals328 and 368 (e.g., messages, indications, information, pilots, and soon), respectively, in accordance with the designated RAT. Specifically,the transceivers 320 and 360 include one or more transmitters 324 and364, respectively, for transmitting and encoding signals 328 and 368,respectively, and one or more receivers 322 and 362, respectively, forreceiving and decoding signals 328 and 368, respectively.

Transceiver circuitry including a transmitter and a receiver maycomprise an integrated device (e.g., embodied as a transmitter circuitand a receiver circuit of a single communication device) in someimplementations, may comprise a separate transmitter device and aseparate receiver device in some implementations, or may be embodied inother ways in other implementations. In an aspect, a transmitter mayinclude or be coupled to a plurality of antennas (e.g., antennas 316,336, and 376), such as an antenna array, that permits the respectiveapparatus to perform transmit “beamforming,” as described herein.Similarly, a receiver may include or be coupled to a plurality ofantennas (e.g., antennas 316, 336, and 376), such as an antenna array,that permits the respective apparatus to perform receive beamforming, asdescribed herein. In an aspect, the transmitter and receiver may sharethe same plurality of antennas (e.g., antennas 316, 336, and 376), suchthat the respective apparatus can only receive or transmit at a giventime, not both at the same time. A wireless communication device (e.g.,one or both of the transceivers 310 and 320 and/or 350 and 360) of theapparatuses 302 and/or 304 may also comprise a network listen module(NLM) or the like for performing various measurements.

The apparatuses 302 and 304 also include, at least in some cases, globalpositioning systems (GPS) receivers 330 and 370. The GPS receivers 330and 370 may be connected to one or more antennas 336 and 376,respectively, for receiving GPS signals 338 and 378, respectively. TheGPS receivers 330 and 370 may comprise any suitable hardware and/orsoftware for receiving and processing GPS signals 338 and 378,respectively. The GPS receivers 330 and 370 request information andoperations as appropriate from the other systems, and performscalculations necessary to determine the apparatus' 302 and 304 positionsusing measurements obtained by any suitable GPS algorithm.

The base station 304 and the network entity 306 each include at leastone network interfaces 380 and 390 for communicating with other networkentities. For example, the network interfaces 380 and 390 (e.g., one ormore network access ports) may be configured to communicate with one ormore network entities via a wire-based or wireless backhaul connection.In some aspects, the network interfaces 380 and 390 may be implementedas transceivers configured to support wire-based or wireless signalcommunication. This communication may involve, for example, sending andreceiving: messages, parameters, or other types of information.

The apparatuses 302, 304, and 306 also include other components that maybe used in conjunction with the operations as disclosed herein. The UE302 includes processor circuitry implementing a processing system 332for providing functionality relating to, for example, RTT measurementsin a licensed or unlicensed frequency band as disclosed herein and forproviding other processing functionality. The base station 304 includesa processing system 384 for providing functionality relating to, forexample, RTT measurements in a licensed or unlicensed frequency band asdisclosed herein and for providing other processing functionality. Thenetwork entity 306 includes a processing system 394 for providingfunctionality relating to, for example, RTT measurements in a licensedor unlicensed frequency band as disclosed herein and for providing otherprocessing functionality. In an aspect, the processing systems 332, 384,and 394 may include, for example, one or more general purposeprocessors, multi-core processors, ASICs, digital signal processors(DSPs), field programmable gate arrays (FPGA), or other programmablelogic devices or processing circuitry.

The apparatuses 302, 304, and 306 include memory circuitry implementingmemory components 340, 386, and 396 (e.g., each including a memorydevice), respectively, for maintaining information (e.g., informationindicative of reserved resources, thresholds, parameters, and so on). Insome cases, the apparatuses 302, 304, and 306 may include RTTpositioning modules 342, 388, and 398, respectively. The RTT positioningmodules 342, 388, and 398 may be hardware circuits that are part of orcoupled to the processing systems 332, 384, and 394, respectively, that,when executed, cause the apparatuses 302, 304, and 306 to perform thefunctionality described herein. Alternatively, the RTT positioningmodules 342, 388, and 398 may be memory modules (as shown in FIGS. 3A-C)stored in the memory components 340, 386, and 396, respectively, that,when executed by the processing systems 332, 384, and 394, cause theapparatuses 302, 304, and 306 to perform the functionality describedherein.

The UE 302 may include one or more sensors 344 coupled to the processingsystem 332 to provide movement and/or orientation information that isindependent of motion data derived from signals received by the WWANtransceiver 310, the WLAN transceiver 320, and/or the GPS receiver 330.By way of example, the sensor(s) 344 may include an accelerometer (e.g.,a micro-electrical mechanical systems (MEMS) device), a gyroscope, ageomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometricpressure altimeter), and/or any other type of movement detection sensor.Moreover, the sensor(s) 344 may include a plurality of different typesof devices and combine their outputs in order to provide motioninformation. For example, the sensor(s) 344 may use a combination of amulti-axis accelerometer and orientation sensors to provide the abilityto compute positions in 2D and/or 3D coordinate systems.

In addition, the UE 302 includes a user interface 346 for providingindications (e.g., audible and/or visual indications) to a user and/orfor receiving user input (e.g., upon user actuation of a sensing devicesuch a keypad, a touch screen, a microphone, and so on). Although notshown, the apparatuses 304 and 306 may also include user interfaces.

Referring to the processing system 384 in more detail, in the downlink,IP packets from the network entity 306 may be provided to the processingsystem 384. The processing system 384 may implement functionality for anRRC layer, a packet data convergence protocol (PDCP) layer, a radio linkcontrol (RLC) layer, and a medium access control (MAC) layer. Theprocessing system 384 may provide RRC layer functionality associatedwith broadcasting of system information (e.g., master information block(MIB), system information blocks (SIBs)), RRC connection control (e.g.,RRC connection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter-RAT mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, scheduling informationreporting, error correction, priority handling, and logical channelprioritization.

The transmitter 354 and the receiver 352 may implement Layer-1functionality associated with various signal processing functions.Layer-1, which includes a physical (PHY) layer, may include errordetection on the transport channels, forward error correction (FEC)coding/decoding of the transport channels, interleaving, rate matching,mapping onto physical channels, modulation/demodulation of physicalchannels, and MIMO antenna processing. The transmitter 354 handlesmapping to signal constellations based on various modulation schemes(e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an orthogonalfrequency division multiplexing (OFDM) subcarrier, multiplexed with areference signal (e.g., pilot) in the time and/or frequency domain, andthen combined together using an Inverse Fast Fourier Transform (IFFT) toproduce a physical channel carrying a time domain OFDM symbol stream.The OFDM stream is spatially precoded to produce multiple spatialstreams. Channel estimates from a channel estimator may be used todetermine the coding and modulation scheme, as well as for spatialprocessing. The channel estimate may be derived from a reference signaland/or channel condition feedback transmitted by the UE 302. Eachspatial stream may then be provided to one or more different antennas356. The transmitter 354 may modulate an RF carrier with a respectivespatial stream for transmission.

At the UE 302, the receiver 312 receives a signal through its respectiveantenna(s) 316. The receiver 312 recovers information modulated onto anRF carrier and provides the information to the processing system 332.The transmitter 314 and the receiver 312 implement Layer-1 functionalityassociated with various signal processing functions. The receiver 312may perform spatial processing on the information to recover any spatialstreams destined for the UE 302. If multiple spatial streams aredestined for the UE 302, they may be combined by the receiver 312 into asingle OFDM symbol stream. The receiver 312 then converts the OFDMsymbol stream from the time-domain to the frequency domain using a fastFourier transform (FFT). The frequency domain signal comprises aseparate OFDM symbol stream for each subcarrier of the OFDM signal. Thesymbols on each subcarrier, and the reference signal, are recovered anddemodulated by determining the most likely signal constellation pointstransmitted by the base station 304. These soft decisions may be basedon channel estimates computed by a channel estimator. The soft decisionsare then decoded and de-interleaved to recover the data and controlsignals that were originally transmitted by the base station 304 on thephysical channel. The data and control signals are then provided to theprocessing system 332, which implements Layer-3 and Layer-2functionality.

In the UL, the processing system 332 provides demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, and control signal processing to recover IP packets fromthe core network. The processing system 332 is also responsible forerror detection.

Similar to the functionality described in connection with the DLtransmission by the base station 304, the processing system 332 providesRRC layer functionality associated with system information (e.g., MIB,SIBs) acquisition, RRC connections, and measurement reporting; PDCPlayer functionality associated with header compression/decompression,and security (ciphering, deciphering, integrity protection, integrityverification); RLC layer functionality associated with the transfer ofupper layer PDUs, error correction through ARQ, concatenation,segmentation, and reassembly of RLC SDUs, re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing ofMAC SDUs from TBs, scheduling information reporting, error correctionthrough HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by the channel estimator from a referencesignal or feedback transmitted by the base station 304 may be used bythe transmitter 314 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the transmitter 314 may be provided to different antenna(s)316. The transmitter 314 may modulate an RF carrier with a respectivespatial stream for transmission.

The UL transmission is processed at the base station 304 in a mannersimilar to that described in connection with the receiver function atthe UE 302. The receiver 352 receives a signal through its respectiveantenna(s) 356. The receiver 352 recovers information modulated onto anRF carrier and provides the information to the processing system 384.

In the UL, the processing system 384 provides demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, control signal processing to recover IP packets from theUE 302. IP packets from the processing system 384 may be provided to thecore network. The processing system 384 is also responsible for errordetection.

For convenience, the apparatuses 302, 304, and/or 306 are shown in FIGS.3A-C as including various components that may be configured according tothe various examples described herein. It will be appreciated, however,that the illustrated blocks may have different functionality indifferent designs.

The various components of the apparatuses 302, 304, and 306 maycommunicate with each other over data buses 334, 382, and 392,respectively. The components of FIGS. 3A-C may be implemented in variousways. In some implementations, the components of FIGS. 3A-C may beimplemented in one or more circuits such as, for example, one or moreprocessors and/or one or more ASICs (which may include one or moreprocessors). Here, each circuit may use and/or incorporate at least onememory component for storing information or executable code used by thecircuit to provide this functionality. For example, some or all of thefunctionality represented by blocks 310 to 346 may be implemented byprocessor and memory component(s) of the UE 302 (e.g., by execution ofappropriate code and/or by appropriate configuration of processorcomponents). Similarly, some or all of the functionality represented byblocks 350 to 388 may be implemented by processor and memorycomponent(s) of the base station 304 (e.g., by execution of appropriatecode and/or by appropriate configuration of processor components). Also,some or all of the functionality represented by blocks 390 to 398 may beimplemented by processor and memory component(s) of the network entity306 (e.g., by execution of appropriate code and/or by appropriateconfiguration of processor components). For simplicity, variousoperations, acts, and/or functions are described herein as beingperformed “by a UE,” “by a base station,” “by a positioning entity,”etc. However, as will be appreciated, such operations, acts, and/orfunctions may actually be performed by specific components orcombinations of components of the UE, base station, positioning entity,etc., such as the processing systems 332, 384, 394, the transceivers310, 320, 350, and 360, the memory components 340, 386, and 396, the RTTpositioning modules 342, 388, and 398, etc.

A simplified environment is shown in FIG. 4 for illustrating anexemplary technique for determining a position of a UE 104. The UE 104may communicate wirelessly with a plurality of gNodeBs 402-406 usingradio frequency (RF) signals and standardized protocols for themodulation of the RF signals and the exchanging of information packets.By extracting different types of information from the exchanged signals,and utilizing the layout of the network (i.e., the network geometry) theUE 104 or any of the gNodeBs 402-406 may determine the UE 104's positionin a predefined reference coordinate system. As shown in FIG. 4, theposition (x, y) of the UE 104 may be specified using a two-dimensionalcoordinate system; however, the aspects disclosed herein are not solimited, and may also be applicable to determining positions using athree-dimensional coordinate system, if the extra dimension is desired.Additionally, while three gNodeBs 402-406 are shown in FIG. 4, aspectsmay utilize additional gNodeBs.

If the UE 104 is to determine its position (x, y), the UE 104 may firstneed to determine the network geometry. The network geometry can includethe positions of each of the gNodeBs 402-406 in a reference coordinatesystem ((x_(k), y_(k)), where k=1, 2, 3). The network geometry may beprovided to the UE 104 in any manner, such as, for example, providingthis information in beacon signals, providing the information using adedicated server external on an external network, providing theinformation using uniform resource identifiers, providing theinformation through base station almanac (BSA), etc.

In determining the position of the UE 104, whether by the UE 104(UE-based) or by the network (UE-assisted), a distance (d_(k), wherek=1, 2, 3) of the UE 104 to each of the gNodeBs 402-406 is determined.As will be described in more detail below, there are a number ofdifferent approaches for estimating these distances (d_(k)) byexploiting different characteristics of the RF signals exchanged betweenthe UE 104 and gNodeBs 402-406. Such characteristics may include, aswill be discussed below, the roundtrip propagation time of the signals.

In other aspects, the distances (d_(k)) may in part be determined orrefined using other sources of information that are not associated withthe gNodeBs 402-406. For example, other positioning systems, such asGPS, may be used to provide a rough estimate of d_(k).

(Note that it is likely that GPS may have insufficient signal in theanticipated operating environments (indoors, metropolitan, etc.) toprovide a consistently accurate estimate of d_(k). However GPS signalsmay be combined with other information to assist in the positiondetermination process.) Other relative positioning devices may reside inthe UE 104 which can be used as a basis to provide rough estimates ofrelative position and/or direction (e.g., on-board accelerometers).

Once each distance d_(k) is determined, the UE 104's position (x, y) maybe solved by using a variety of known geometric techniques, such as, forexample, trilateration. From FIG. 4, it can be seen that the position ofthe UE 104 ideally lies at the intersection of the circles (or spheres)drawn using dotted lines. Each circle (or sphere) being defined byradius d_(k) and center (x_(k), y_(k)), where k=1, 2, 3. In practice,the intersection of these circles (or spheres) may not lie at a singlepoint due to the noise and other errors in the networking system.

Determining the distance between the UE 104 and each gNodeB 402-406 mayinvolve exploiting time information of the RF signals. In an aspect,determining the RTT of signals exchanged between the UE 104 and a gNodeB402-406 can be performed and converted to a distance (d_(k)). RTTtechniques can measure the time between sending a data packet andreceiving a response. These methods utilize calibration to remove anyprocessing delays. In some environments, it may be assumed that theprocessing delays for the UE 104 and the gNodeBs 402-406 are the same.However, such an assumption may not be true in practice.

A position estimate (e.g., for a UE 104) may be referred to by othernames, such as a location estimate, location, position, position fix,fix, or the like. A position estimate may be geodetic and comprisecoordinates (e.g., latitude, longitude, and possibly altitude) or may becivic and comprise a street address, postal address, or some otherverbal description of a location. A position estimate may further bedefined relative to some other known location or defined in absoluteterms (e.g., using latitude, longitude, and possibly altitude). Aposition estimate may include an expected error or uncertainty (e.g., byincluding an area or volume within which the location is expected to beincluded with some specified or default level of confidence).

As mentioned above, OTDOA and RTT are techniques to determine a positionof a UE. However, they both have their limitations. In OTDOA,synchronizing time among the gNodeBs at their Tx antennas is animportant factor for positioning accuracy. Unfortunately, this can becomplex to maintain. Otherwise, the frame-boundaries identified by theUE from different gNodeBs can have arbitrary timing relations, which inturn can lead to compromising the accuracy of the UE's positiondetermination. It should be noted that maintaining synchronization at Txantennas of the gNodeBs involves measuring the delay between the digitaldomain and physical transmission or ensuring they are the same fordifferent gNodeBs.

Another factor for achieving positioning accuracy in OTDOA is that groupdelay from physical signal reception at the UE Rx antennas to conversionto the digital domain (where TDOAs are measured) be the same for allgNodeBs measured. Alternatively, differences in group delays can beallowed, but the differences should be compensated for to achieve thedesired positioning accuracy. The quantity of interest is the flighttime between the Tx and Rx antennas, which should exclude thisgroup-delay. However, since TDOA is used, only differences in the groupdelays are of significance, not the absolute group delays.

With RTT on the other hand, maintaining time synchronization among thegNodeBs is not necessary for position determination. This is because aseparate ranging procedure can be followed by the UE with each gNodeB.However, to avoid over-estimating the range, determining absolute valuesof the group delays can be very beneficial.

The concept of group delays will be described with respect to FIGS. 5Aand 5B. FIG. 5A illustrates an RTT scenario between a transmitter 502and a receiver 504, and FIG. 5B is a diagram showing exemplary timingswithin an RTT occurring during a wireless probe request and a responsebetween the transmitter 502 and the receiver 504. For a network centric(UE-assisted) RTT determination, the transmitter 502 may correspond to anetwork node (e.g., any of the base stations described herein) and thereceiver 504 may correspond to a UE (e.g., any of the UEs describedherein). For a UE centric RTT determination, the transmitter 502 maycorrespond to the UE and the receiver 504 may correspond to the networknode.

To determine the RTT (and hence distance) between the transmitter 502and the receiver 504, the transmitter 502 sends an RTT measurement(RTTM) signal at a first time, referred to as “t1.” After somepropagation time, the receiver 504 detects that the RTTM signal isreceived at a second time, referred to as “t2.” Subsequently, thereceiver 504 takes some turn-around time “Δ” to process the receivedRTTM signal before sending an RTT response (RTTR) signal at a thirdtime, referred to as “t3.” After the propagation time, the transmitter502 detects that the RTTR signal is received at a fourth time, referredto as “t4.” Thus, the measured flight time or RTT (referred to as “tp”for “propagation time”) may be calculated as:

measured RTT=(t4−t1)−(t3−t2),  (1)

where (t4−t1) is the measured total time, and (t3−t2) is the measuredturn-around time at the receiver 504.

Times t1, t2, t3, and t4 are the times as measured by the transmitter502 and the receiver 504 in the digital domain. However, in reality, theRTTM signal actually leaves the transmitter 502 at some time after t1,referred to as “t1′,” and arrives at the receiver 504 at some timebefore t2, referred to as “t2′.” Also, the RTTR signal actually leavesthe receiver 504 at some time after t3, referred to as “t3′,” andarrives at the transmitter 502 at some time before t4, referred to as“t4′.” This means that the actual flight time or RTT (referred to as“tp′”) is as follows:

actual RTT=(t4′−t1′)−(t3′−t2′),  (2)

where (t4′−t1′) is the actual total time, and (t3′−t2′) is the actualturn-around time at the receiver 504.

The discrepancy between the measured times (e.g., t1, t2, t3, t4) andthe actual times (e.g., t1′, t2′, t3′, t4′) is explained as follows. Inwireless communications, a source device (or simply “source”) transmitssignals to a destination device (or simply “destination”). In order totransmit a digital signal, a Tx RF chain (also referred to as an RFfront end (RFFE)) at the source performs a process to convert thedigital signal into an RF signal. For example, the source's Tx RF chain(or simply “Tx chain”) can include a digital-to-analog converter (DAC)to convert the digital signal into a baseband analog signal, anupconverter to upconvert the baseband signal into an RF signal, and apower amplifier (PA) to amplify the RF signal, which is then radiatedfrom the antenna(s) of the source.

The destination can include an Rx RF chain (or simply “Rx chain”) toperform a reverse process to retrieve the original digital signal fromthe arriving RF signal. For example, the destination's Rx RF chain (orsimply “Rx chain”) can include a filter (e.g., low pass, high pass, bandpass) to filter the RF signal received by the antenna(s) of thedestination, a low noise amplifier (LNA) to amplify the filtered RFsignal, a downconverter to downconvert the filtered RF signal into thebaseband signal, and an analog-to-digital (ADC) converter to recover thedigital signal from the baseband signal.

The process performed by the source's Tx chain to convert the digitalsignal onto the RF signal takes a finite amount of time (genericallyreferred to as “Tx group delay”). The Tx group delay may be said torepresent a delay between a measured transmission time of a signal andan actual time of the signal leaving the source (e.g., t1′−t1). Thereverse process performed by the destination's Rx chain to recover thedigital signal from the RF signal also takes a finite amount of time(generically referred to as “Rx group delay”). The Rx group delay may besaid to represent the delay between an actual time of a signal arrivingat the destination and a measured arrival time of the signal (e.g.,t2−t2′).

The term “group delay” is used to emphasize that the delay is caused byelements in the Tx/Rx chain as described above, which may includefilters, and may result in a delay that is a function of frequency, RAT,carrier aggregation (CA), component carrier (CC), and so on.

With continued reference to FIGS. 5A and 5B, it is seen that each of thetransmitter 502 and the receiver 504 includes both the Tx and Rx groupdelays. The total group delay (or simply “group delay”) for each devicemay be determined by summing their respective Tx and Rx group delays.Then, the group delay (GD) for the transmitter 502 may be expressed as:

GD=(t1′−t1)+(t4−t4′).  (3)

Also, the GD for the receiver 504 may be expressed as:

GD=(t3′−t3)+(t2−t2′).  (4)

From equations (1) and (2), it will be appreciated that if the RTTmeasurements are based on the measured times alone, then the distancebetween the transmitter 502 and the receiver 504 can be overestimated.However, if the group delays can be accounted for, then the actual RTTcan be determined. This illustrates that for RTT, accurate determinationof the group delays is important.

As mentioned above, inter-gNodeB timing synchronization and group delaysare factors that affect positioning accuracies for both OTDOA and RTTtechniques. But also as mentioned above, for OTDOA, while tightinter-gNodeB timing synchronization is important, loose group delays canbe tolerated. But for RTT, it is the other way around. That is, tightgroup delays are important, but loose inter-gNodeB timingsynchronization can be tolerated. Both requirements should be such thatthey do not limit positioning accuracy. With tighter accuracy targets inNR (e.g., centimeter-level for factory automation scenarios), theserequirements also need to be tighter.

To address these issues, it is proposed perform a differential RTT basedpositioning procedure to determine a position of the UE. Broadly, thedifferential RTT based positioning procedure may be viewed as atechnique to determine a position of the UE (UE position) based ondifferences of RTTs among a plurality of RTTs. The proposed differentialRTT based positioning allows for looser inter-gNodeB synchronizationrelative to the conventional OTDOA technique. At the same time, theproposed differential RTT based positioning procedure allows for loosergroup delays relative to conventional RTT techniques. In other words,the differential RTT based positioning procedure described herein hasthe advantages of both the conventional OTDOA and RTT techniques,without their disadvantages. This can also lead to lower complexity anddevice cost.

FIG. 6 illustrates an example method 600 performed by a network node todetermine a UE position, according to aspects of the disclosure. In anaspect, the network node may be a location server (e.g., location server230, LMF 270) or other positioning entity, and may be located in thecore network (e.g., NGC 260), in the RAN (e.g., at the serving basestation), or at the UE (e.g., for UE-based positioning).

At 610, the network node may collect a plurality of RTTs between a UEand a plurality of base stations (e.g., gNodeBs). Each RTT may beassociated with a single BS of the plurality of BSs. Each RTT mayrepresent a total flight time of an RTT signal back and forth betweenthe UE and the associated BS. For example, each RTT may represent theflight times of the RTTM and RTTR signals (see FIGS. 5A, 5B) between theUE and the associated BS.

In an aspect, where the network node is a network entity, operation 610may be performed by the network interface(s) 390, the processing system394, the memory 396, and/or the RTT positioning module 398, any or allof which may be considered means for performing this operation. In anaspect, where the network node is a base station, operation 610 may beperformed by WWAN transceiver 350, the network interface(s) 380, theprocessing system 384, the memory 386, and/or the RTT positioning module388, any or all of which may be considered means for performing thisoperation. In an aspect, where the network node is a UE, operation 610may be performed by the WWAN transceiver 310, the processing system 332,the memory 340, and/or the RTT positioning module 342, any or all ofwhich may be considered means for performing this operation.

In one aspect, collecting the plurality of RTTs may involve receivingone or more RTT reports from the UE in which the one or more RTT reportsinclude the plurality of RTTs. In this aspect, it may be assumed thatthe UE determines the RTTs. For example, the UE may determine the RTTsbetween itself and the BSs. If the BS serving the UE (e.g., servinggNodeB) is the network node, the network node may receive the one ormore RTT reports directly. On the other hand, if the serving BS is notthe network node, the one or more RTT reports may be received from theUE via the serving BS.

In another aspect, collecting the plurality of RTTs may involvereceiving the one or more RTT reports from the serving BS. In thisaspect, it may be assumed that the RTTs are determined on the networkside. For example, each BS may determine the RTT between itself and theUE, and report the RTT to the serving BS. The serving BS in turn maygather the RTTs from the BSs into the one or more RTT reports andprovide the one or more RTT reports to the UE. The serving BS may itselfdetermine the RTT between itself and the UE, which may be included inthe plurality of RTTs of the one or more RTT reports.

In yet another aspect, if the serving BS is the network node and theRTTs are determined on the network side, then collecting the pluralityof RTTs may involve gathering the RTTs from the from the BSs (includingitself). In general, computing each RTT involves a measurement by boththe nodes (e.g., a UE and a gNB) between which the RTT procedure iscarried out. The positioning engine, or location server, that computesthe final position, receives these measurements for multiple RTTprocedures between the UE and the multiple base stations, or receivesthe RTTs directly, where each RTT has been computed by another node thatreceived both the needed measurements. The positioning engine may bephysically located in the UE, the base station, or elsewhere in thenetwork. The nodes involved in computing RTTs, communicating the RTTrelated measurements, or the RTTs may also be the UE, base station, orother network node. Special examples of this (e.g., with the locationserver located in the base station) were described earlier, but it is tobe understood that the disclosure is not limited to these examples.

At 620, the network node may receive group delay parameters. These areparameters related to the plurality of RTTs. If the plurality of RTTs isreceived from the UE, the group delay parameters may also be receivedfrom the UE. For example, the group delay parameters may be included inone or more positioning protocol signals from the UE. Examples of thepositioning protocol signals include LTE positioning protocol (LPP)signal. As another example, the group delay parameters may be receivedfrom the UE separately from the plurality of RTTs, such as in capabilityinformation of the UE.

In an aspect, where the network node is a network entity, operation 620may be performed by the network interface(s) 390, the processing system394, the memory 396, and/or the RTT positioning module 398, any or allof which may be considered means for performing this operation. In anaspect, where the network node is a base station, operation 620 may beperformed by the WWAN transceiver 350, the network interface(s) 380, theprocessing system 384, the memory 386, and/or the RTT positioning module388, any or all of which may be considered means for performing thisoperation. In an aspect, where the network node is a UE, operation 620may be performed by the WWAN transceiver 310, the processing system 332,the memory 340, and/or the RTT positioning module 342, any or all ofwhich may be considered means for performing this operation.

If the plurality of RTTs is received from the network, such as from theserving BS, the group delay parameters may also be received from theserving BS. For example, the group delay parameters may be included inone or more positioning protocol annex signals from the serving BS.Examples of the positioning protocol annex signals include LTEpositioning protocol annex (LPPa) signaling and New Radio positioningprotocol annex (NR-PPa) signaling.

If the serving BS is the network node and the RTTs are determined on thenetwork side, information related to the group delay parameters may begathered from the other BSs, such as through one or more backhaullinks/interfaces.

At 630, the network node may determine whether the UE and/or the BSgroup delays are included in the plurality of RTTs. In one aspect, thegroup delay parameters received at 620 from the UE or the serving BS mayinclude an RTT type parameter indicating whether the plurality of RTTsis a plurality of measured RTTs or actual RTTs. Recall that the measuredRTT (e.g., (t4−t1)−(t3−t2)) is in the digital domain, which does notfactor out the group delays. Therefore, if the RTT type parameterindicates that the plurality of RTTs is a plurality of measured RTTs,then it may be determined that the group delays are included in theplurality of RTTs. On the other hand, if the RTT type parameterindicates that the plurality of RTTs is a plurality of actual RTTs, thismeans that the group delays have been factored out.

In an aspect, where the network node is a network entity, operation 630may be performed by the processing system 394, the memory 396, and/orthe RTT positioning module 398, any or all of which may be consideredmeans for performing this operation. In an aspect, where the networknode is a base station, operation 630 may be performed by the processingsystem 384, the memory 386, and/or the RTT positioning module 388, anyor all of which may be considered means for performing this operation.In an aspect, where the network node is a UE, operation 630 may beperformed by the processing system 332, the memory 340, and/or the RTTpositioning module 342, any or all of which may be considered means forperforming this operation.

If at 630 it is determined that the plurality of RTTs do not include theUE group delays and also do not include the BS group delays (“N” branchfrom 630), then the method 600 may proceed to 640 to determine the UEposition through an absolute RTT based positioning procedure. When thegroup delays are not included in the plurality of RTTs, this means eachRTT is an actual RTT (e.g., (t4′−t1 ‘)−(t3’−t2′)). To state it anotherway, the groups delays have been taken into account when the RTTs do notinclude the group delays.

FIG. 7 illustrates an example process performed by the network node toimplement the absolute RTT based positioning technique at 640. Note thatif the RTTs are actual RTTs, concerns with overestimating the actualdistances are reduced. Therefore, at 710, the network node may determinean absolute RTT set based on the plurality of RTTs. The absolute RTT setmay comprise one or more absolute members. Each absolute member maycorrespond to one of the RTTs, i.e., correspond to one of the BSs. Eachabsolute member may represent an absolute distance between the UE andthe corresponding BS calculated based on the RTT associated with thecorresponding BS.

In an aspect, where the network node is a network entity, operation 710may be performed by the processing system 394, the memory 396, and/orthe RTT positioning module 398, any or all of which may be consideredmeans for performing this operation. In an aspect, where the networknode is a base station, operation 710 may be performed by the processingsystem 384, the memory 386, and/or the RTT positioning module 388, anyor all of which may be considered means for performing this operation.In an aspect, where the network node is a UE, operation 710 may beperformed by the processing system 332, the memory 340, and/or the RTTpositioning module 342, any or all of which may be considered means forperforming this operation.

At 720, the network node may determine the UE position based on theabsolute RTT set. For example, assuming that the physical locations ofthe BSs are known, each absolute distance can be translated into anappropriately sized circle (or sphere) with the associated BS at itscenter. The UE position may be then determined from the intersections ofthe circles (or spheres). It is to be noted that many differentprocedures could be used to compute the location of the intersection.For example, the location may be computed by an analytical formulainvolving the base station location coordinates r₁ and correspondingUE-to-base station distances D₁ estimated by the RTT procedure betweenthe UE and the i-th base station. In another example, an iterativescheme may be used to find the location coordinate vector r thatminimizes a cost function such as the sum of ∥r-r_(i)|−D_(i)| or∥r-r_(i)|²−D_(i) ²| over all base stations T, where |x| represents thedistance of the point with coordinate vector x from the origin of thecoordinate frame used to describe the coordinate vectors. The scope ofthe step described as “determining the intersections of circles (orspheres)” encompasses any such procedures.

In an aspect, where the network node is a network entity, operation 720may be performed by the processing system 394, the memory 396, and/orthe RTT positioning module 398, any or all of which may be consideredmeans for performing this operation. In an aspect, where the networknode is a base station, operation 720 may be performed by the processingsystem 384, the memory 386, and/or the RTT positioning module 388, anyor all of which may be considered means for performing this operation.In an aspect, where the network node is a UE, operation 720 may beperformed by the processing system 332, the memory 340, and/or the RTTpositioning module 342, any or all of which may be considered means forperforming this operation.

Note that the number of absolute members in the absolute RTT set neednot be equal to the number of RTTs in the plurality of RTTs. In mostinstances, three RTTs may be necessary (to generate three circles orspheres) to narrow the UE position to a single location in twodimensions, and four RTTs may be necessary (to generate four spheres) tonarrow the UE position to a single location in three dimensions.Additional RTTs, while not strictly necessary, can increase thepositioning accuracy.

Referring back to FIG. 6, if it is determined that the plurality of RTTsdo include the UE group delays and/or the BS group delays (middle “Y”branch from 630), then in one aspect, the method 600 may proceed to 650to determine the UE position through the differential RTT basedpositioning. Unlike the absolute RTT based positioning technique, thedifferential RTT based positioning technique is much less sensitive tothe presence of group delays. This is because the effects of the groupdelay in one RTT are canceled, at least in part, by the group delay inanother RTT.

FIG. 8 illustrates an example process performed by the network node toimplement the differential RTT based positioning technique at 650.Broadly, the differential RTT based positioning may be described asdetermining the UE position based on the differences of the RTTs amongthe plurality of RTTs.

At 810, the network node may determine a reference BS among theplurality of BSs. In an aspect, where the network node is a networkentity, operation 810 may be performed by the processing system 394, thememory 396, and/or the RTT positioning module 398, any or all of whichmay be considered means for performing this operation. In an aspect,where the network node is a base station, operation 810 may be performedby the processing system 384, the memory 386, and/or the RTT positioningmodule 388, any or all of which may be considered means for performingthis operation. In an aspect, where the network node is a UE, operation810 may be performed by the processing system 332, the memory 340,and/or the RTT positioning module 342, any or all of which may beconsidered means for performing this operation.

At 820, the network node may determine a differential RTT set based onthe plurality of RTTs. The differential RTT set may comprise one or moredifferential members. Each differential member may correspond to one ofthe RTTs, i.e., correspond to one of the BSs other than the referenceBS. Each differential member may represent a differential distancecalculated based on a difference in the RTT associated with thereference BS and the RTT associated with the corresponding BS. Morespecifically, a “differential member” represents a quantity d(UE,node1)-d(UE, node2), where d(UE, nodeN) is the distance between the UEand the node N (e.g., a base station). One of node1 and node2 may be areference node, meaning that it is chosen as one of the two nodes forall the differential members. In an aspect, where the network node is anetwork entity, operation 820 may be performed by the processing system394, the memory 396, and/or the RTT positioning module 398, any or allof which may be considered means for performing this operation. In anaspect, where the network node is a base station, operation 820 may beperformed by the processing system 384, the memory 386, and/or the RTTpositioning module 388, any or all of which may be considered means forperforming this operation. In an aspect, where the network node is a UE,operation 820 may be performed by the processing system 332, the memory340, and/or the RTT positioning module 342, any or all of which may beconsidered means for performing this operation.

At 830, the network node may determine the UE position based on thedifferential RTT set. For example, assuming that the physical locationsof the BSs are known, each differential distance, based on a pair ofBSs, implies for the case of two-dimensional positioning, that the UE islocated on a hyperbola with the locations of those two BSs as the foci.The UE position on the two-dimensional plane may then be determined fromthe intersections of the hyperbolas. In the case of three-dimensionalpositioning, the hyperbola is replaced by the hyperboloid surfaceobtained by revolving the hyperbola around the axis passing through thefoci, and the UE's position is obtained as the intersection of thesehyperboloids. As described earlier for the case of intersections ofcircles (or spheres) when absolute RTT is used, the intersections of thehyperbolas (or hyperboloids) may be computed using many differentprocedures, and the scope of the disclosure includes any such procedure.In an aspect, where the network node is a network entity, operation 830may be performed by the processing system 394, the memory 396, and/orthe RTT positioning module 398, any or all of which may be consideredmeans for performing this operation. In an aspect, where the networknode is a base station, operation 830 may be performed by the processingsystem 384, the memory 386, and/or the RTT positioning module 388, anyor all of which may be considered means for performing this operation.In an aspect, where the network node is a UE, operation 830 may beperformed by the processing system 332, the memory 340, and/or the RTTpositioning module 342, any or all of which may be considered means forperforming this operation.

Note that the number of differential members in the differential RTT setneed not be equal to the number of RTTs in the plurality of RTTs. Inmost instances, four RTTs may be necessary (to generate threehyperbolas) to narrow the UE position to a single location in twodimensions, and five RTTs may be necessary (to generate four hyperbolas)to narrow the UE position to a single location in three dimensions.Additional RTTs, while not strictly necessary, can increase theaccuracy. More specifically, with only two hyperbolas in a plane, therecould be two intersection points. The third hyperbola allowsdisambiguating between these two points. The number of hyperbolas is oneless than the number of RTTs because each hyperbola corresponds to adifference between two RTTs. Note that the hyperbolas to be used shouldcorrespond to independent differential members, i.e., with three nodes,there are three RTTs (e.g., a, b, c), and three differential memberscould be formed, a-b, a-c, and b-c. However, but only two of these wouldbe useful because the third is derivable from the other two, e.g.,b-c=(a-c)−(a-b).

Recall that the differential RTT based positioning is advantageous inthat both the inter-gNodeB synchronization and group delay requirementscan be loosened. The tradeoff is that in the differential RTT basedpositioning technique, one of the observations—the RTT of the referenceBS—is lost. However, when there are more RTTs than the minimum required,the tradeoff cost can be minimal.

As indicated above, the differential RTT based positioning technique ismuch less sensitive to the presence of group delays relative to theabsolute RTT based technique. Referring back to FIG. 6, the middle Ybranch from 630 to 650 indicates an aspect in which the differential RTTbased positioning technique is used whenever the plurality of RTTsinclude the group delays, i.e., are measured RTTs.

While the differential RTT based positioning procedure is less sensitiveto the group delays, it may not be completely insensitive. When thereare differences in the group delays in the plurality of RTTs,inaccuracies can be introduced when the UE position is calculated. Notethat the UE group delays in the RTTs may be of little to no concern.This is because when differentials are taken, the UE group delays in theRTTs are canceled. However, BS group delays may be of some concern sincedifferent BSs may have different BS group delays.

Therefore, in another aspect, if the plurality of RTTs do include the UEgroup delays and/or the BS group delays (left “Y” branch from 630), themethod 600 may proceed to 660 to determine whether the group delays inthe plurality of RTTs are “sufficiently similar” such that inaccuraciesintroduced due to the differences in the group delays are tolerable. Ifthe group delays, and in particular the BS delays, are determined to besufficiently similar in 660, then the network node may proceed to 650 toperform the differential RTT based positioning.

Block 660 includes decision blocks 662, 664, and 666. The network nodemay perform any combination of these blocks, conjunctive or disjunctive,to determine whether to proceed to 650 or not. In an aspect, the groupdelay parameters received at 620 from the UE or the serving BS mayinclude a group delay difference parameter indicating a difference inthe group delays among the plurality of BSs. More specifically, theparameter needed is the difference between the group delays included indifferent RTT reports (corresponding to different base stations). Eachgroup delay includes a component from the UE and one from the basestation. The UE may indicate the UE component. If the UE used similarconfigurations, such as similar beams, antenna panels, bandwidth, etc.,for both the RTT measurements, then it is likely that the difference inthe UE component is small/negligible. For the base station component, acomparison is needed across different base stations, so it is morechallenging to report their group delay. One way is for each basestation to indicate its own parameters, such as its maximum group delayand expected variance/uncertainty in group delay, and the positioningentity then translates these into group delay difference parameters. Theparameter indicated may also be, for example, a make and model typeindication for the base station, as group delay may be expected to besimilar for two base stations of the same make and model. Another optionis for the base stations to exchange these parameters among themselves(e.g., via the X2 or Xn interface) and one base station to consolidate,compute, and report these group delay difference parameters to thepositioning entity for itself and its one or more neighbors.

At 662, the network node may determine whether or not the differenceindicated by the group delay difference parameter is within a thresholddifference, which may represent a maximum tolerable group delaydifference. The threshold difference may be predetermined and/ordynamically set during operation based on, for example, the requestedpositioning accuracy. If 662 is applied, then it may be said that thedifferential RTT based positioning procedure is performed when the UEand/or BS group delays are included in the plurality of RTTs, and whenthe difference is within the threshold difference.

In another aspect, the group delay parameters or RTT relatedmeasurements (such as Rx-Tx timing difference) received at 620 from theUE or the serving BS may include a group delay uncertainty parameterindicating a level of uncertainty in the group delays among theplurality of B Ss. The value may be based on internal details of how thebase station's RF front-end is implemented. For example, a base stationthat calibrates its group delay (either as part of the factorymanufacturing procedure or on the fly over-the-air) is likely to haveless uncertainty in the group delay, and the uncertainty may depend onhow long ago the calibration took place.

At 664, the network node may determine whether or not the uncertaintyindicated by the group delay uncertainty parameter is within a thresholduncertainty, which may represent a maximum tolerable group delayuncertainty. The threshold uncertainty may be predetermined and/ordynamically set during operation based on, for example, the requestedpositioning accuracy. If 664 is applied, then it may be said thedifferential RTT based positioning procedure is performed when the UEand/or BS group delays are included in the plurality of RTTs, and whenthe uncertainty is within the threshold uncertainty.

In yet another aspect, the group delay parameters received at 620 fromthe UE or the serving BS may include one or more Tx/Rx configurations.Each Tx/Rx configuration may correspond to a BS of the plurality of BSs,and may comprise link parameters associated with a communication linkestablished between the UE and the corresponding BS for determining theRTT there between. Link parameters may include any one or more of Tx/Rxbeams, Tx-power used, bandwidth, component carrier index, frequencyband, RAT (such as LTE or NR), etc. Similar configurations may beassociated with similar group delays. Configuration parameters may alsoinclude details such as the make and/or model of the BS; for example,identical models may be expected to have similar group delays. It shouldbe noted that some parameters, such as bandwidth, may be known to thenetwork, and therefore, need not be reported.

At 666, the network node may determine whether or not differences amongthe Tx/Rx configurations (i.e., differences across different RTTmeasurements) are within a threshold Tx/Rx configuration difference,which may represent a maximum tolerable configuration difference. Thethreshold Tx/Rx configuration difference may be predetermined and/ordynamically set during operation based on, for example, the requestedpositioning accuracy. If 666 is applied, then it may be said thedifferential RTT based positioning is performed when the UE and/or BSgroup delays are included in the plurality of RTTs, and when theconfiguration differences among the Tx/Rx configurations are within thethreshold Tx/Rx configuration difference.

In an aspect, where the network node is a network entity, operations662, 664, and 666 may be performed by the processing system 394, thememory 396, and/or the RTT positioning module 398, any or all of whichmay be considered means for performing this operation. In an aspect,where the network node is a base station, operations 662, 664, and 666may be performed by the processing system 384, the memory 386, and/orthe RTT positioning module 388, any or all of which may be consideredmeans for performing this operation. In an aspect, where the networknode is a UE, operations 662, 664, and 666 may be performed by theprocessing system 332, the memory 340, and/or the RTT positioning module342, any or all of which may be considered means for performing thisoperation.

FIG. 9 illustrates an example method 900 performed by the UE inassisting the network to determine the UE position, according to aspectsof the disclosure. At 910, the UE may determine a plurality of RTTs. Forexample, the UE may exchange RTT signals with a plurality of BSs anddetermine the associated RTTs. If the BSs provide their BS group delays,then the UE may factor out the group delays from the RTTs such that theplurality of RTTs are actual RTTs.

At 920, the UE may provide the plurality of RTTs to the network node inan RTT report. If the UE knows the BS group delays, it may provide theactual RTTs to the network node, or the measured RTTs and the BS groupdelays. Otherwise, it simply provides the measured RTTs. As indicatedabove, the network node may determine whether to perform thedifferential RTT based positioning procedure to determine the UEposition based on the differences of the RTTs among the plurality ofRTTs included in the RTT report.

At 930, based on the UE and/or the BS group delays, the UE may providethe group delay parameters to the network node. The group delayparameters may indicate whether or not the group delays were included inthe RTTs reported at 920, and if so, for which RTTs/BSs. The group delayparameters may be included in one or more positioning protocol signalsto the network node. Examples of the positioning protocol signalsinclude LPP signaling. The group delay parameters may also include anyone or more of the RTT type parameter, the group delay differenceparameter, the group delay uncertainty parameter, and one or more Tx/Rxconfigurations.

Note that while FIG. 9 is described in terms of a UE, one or more basestations may perform a similar method with a single UE.

It should be noted that not all illustrated blocks of FIGS. 6 to 9 needbe performed, i.e., some blocks may be optional. Also, the numericalreferences to the blocks in these figures should not be taken asrequiring that the blocks should be performed in a certain order.Indeed, some blocks may be performed concurrently.

Also, while FIGS. 6 to 9 illustrate network centric (UE-assisted)methods, it is contemplated that the UE itself is capable ofimplementing the differential RTT based positioning to determine its ownposition, if it is provided with the necessary information for UE-basedpositioning, such as the locations of the base stations. Similarly, thepositioning calculation in network-centric scheme could be at abase-station or a core-network entity.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implemented orperformed with a general purpose processor, a DSP, an ASIC, an FPGA, orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor maybe a microprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The methods, sequences and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), flashmemory, read-only memory (ROM), erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), registers, hard disk, aremovable disk, a CD-ROM, or any other form of storage medium known inthe art. An exemplary storage medium is coupled to the processor suchthat the processor can read information from, and write information to,the storage medium. In the alternative, the storage medium may beintegral to the processor. The processor and the storage medium mayreside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). Inthe alternative, the processor and the storage medium may reside asdiscrete components in a user terminal.

In one or more exemplary aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and Blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects of thedisclosure, it should be noted that various changes and modificationscould be made herein without departing from the scope of the disclosureas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the aspects of the disclosuredescribed herein need not be performed in any particular order.Furthermore, although elements of the disclosure may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A method performed by a network node, the methodcomprising: collecting a plurality of round trip times (RTTs) between auser equipment (UE) and a plurality of base stations (BSs), each RTT ofthe plurality of RTTs associated with a BS of the plurality of BSs, andeach RTT representing a total flight time of an RTT signal back andforth between the UE and the associated BS; and performing adifferential RTT based positioning procedure to determine a position ofthe UE based on differences of the RTTs among the plurality of RTTs. 2.The method of claim 1, wherein performing the differential RTT basedpositioning procedure comprises: determining a reference BS among theplurality of BSs; determining a differential RTT set from the pluralityof RTTs, the differential RTT set comprising one or more differentialmembers, each differential member corresponding to a BS other than thereference BS, and each differential member representing a differentialdistance calculated based on a difference in the RTT associated with thereference BS and the RTT associated with the BS corresponding to thedifferential member; and determining the position of the UE based on thedifferential RTT set.
 3. The method of claim 1, wherein collecting theplurality of RTTs comprises receiving one or more RTT reports, the oneor more RTT reports comprising the plurality of RTTs.
 4. The method ofclaim 3, further comprising: determining whether UE and/or BS groupdelays are included in the plurality of RTTs, wherein the differentialRTT based positioning procedure is performed when it is determined thatthe UE and/or BS group delays are included in the plurality of RTTs. 5.The method of claim 4, further comprising: performing an absolute RTTbased positioning procedure to determine the position of the UE when itis determined that the plurality of RTTs do not include the UE groupdelay and do not include the BS group delays, wherein performing theabsolute RTT based positioning procedure comprises: determining anabsolute RTT set based on the plurality of RTTs, the absolute RTT setcomprising one or more absolute members, each absolute membercorresponding to a BS, and each absolute member representing an absolutedistance between the UE and the corresponding BS calculated based on theRTT associated with the corresponding BS; and determining the positionof the UE based on the absolute RTT set.
 6. The method of claim 4,further comprising: receiving one or more group delay parameters fromthe UE and/or at least one of the plurality of BSs, wherein the one ormore group delay parameters comprise an RTT type parameter indicatingwhether the plurality of RTTs are measured RTTs or are actual RTTs, andwherein it is determined that the UE and/or the BS group delays areincluded in the plurality of RTTs when the RTT type parameter indicatesthat the plurality of RTTs are measured RTTs.
 7. The method of claim 6,wherein the one or more group delay parameters further comprise a groupdelay difference parameter indicating a difference in the BS groupdelays among the plurality of BSs, wherein the method further comprisesdetermining whether or not the difference indicated by the group delaydifference parameter is within a threshold difference, and wherein thedifferential RTT based positioning procedure is performed when it isdetermined that the UE and/or BS group delays are included in theplurality of RTTs, and when the difference is within the thresholddifference.
 8. The method of claim 6, wherein the one or more groupdelay parameters further comprise a group delay uncertainty parameterindicating an uncertainty in the BS group delays among the plurality ofBSs, wherein the method further comprises determining whether or not theuncertainty indicated by the group delay uncertainty parameter is withina threshold uncertainty, and wherein the differential RTT basedpositioning procedure is performed when it is determined that the UEand/or BS group delays are included in the plurality of RTTs, and whenthe uncertainty is within the threshold uncertainty.
 9. The method ofclaim 6, wherein the one or more group delay parameters further compriseone or more Tx/Rx configurations, each Tx/Rx configuration correspondingto a BS, each Tx/Rx configuration comprising link parameters associatedwith a communication link established between the UE and thecorresponding BS for determining the RTT there between, wherein themethod further comprises determining whether or not differences amongthe Tx/Rx configurations are within a threshold Tx/Rx configurationdifference, and wherein the differential RTT based positioning procedureis performed when it is determined that the UE and/or BS group delaysare included in the plurality of RTTs, and when the configurationdifferences among the Tx/Rx configurations are within the thresholdTx/Rx configuration difference.
 10. The method of claim 9, wherein thelink parameters comprise any one or more of transmit/receive beams,transmission power used, and bandwidth.
 11. The method of claim 3,wherein the network node comprises a location server.
 12. The method ofclaim 11, wherein the one or more RTT reports are received from areporting BS, the reporting BS being one of the plurality of BSs. 13.The method of claim 12, wherein the one or more RTT reports are includedin LTE positioning protocol annex (LPPa) signaling and/or in New Radiopositioning protocol annex (NR-PPa) signaling from the reporting BS. 14.The method of claim 11, wherein the one or more RTT reports are receivedfrom the UE.
 15. The method of claim 14, wherein the one or more RTTreports are included in LTE positioning protocol (LPP) signaling fromthe UE.
 16. The method of claim 3, wherein the network node comprisesthe UE.
 17. The method of claim 16, wherein the one or more RTT reportsare received from a location server or a reporting BS.
 18. The method ofclaim 3, wherein the network node comprises a reporting BS of theplurality of BSs.
 19. The method of claim 18, wherein the one or moreRTT reports are received from a location server or the UE.
 20. A methodat a wireless device, comprising: providing one or more group delayparameters for the wireless device to a positioning entity, wherein theone or more group delay parameters comprise a round-trip-time (RTT) typeparameter indicating whether RTTs reported by the wireless device aremeasured RTTs or actual RTTs, and wherein it is determined that a groupdelay of the wireless device is included in the reported RTTs when theRTT type parameter indicates that the reported RTTs are measured RTTs.21. The method of claim 20, further comprising: performing a measurementof a reference signal received from another wireless device.
 22. Themethod of claim 21, further comprising: providing, to the positioningentity, an indication of which group delay parameter of the one or moregroup delay parameters applies to the measurement of the referencesignal.
 23. The method of claim 20, further comprising: transmitting theone or more group delay parameters to the positioning entity as part ofcapability information of the wireless device.
 24. The method of claim20, wherein the wireless device comprises a base station.
 25. The methodof claim 24, wherein the one or more group delay parameters furthercomprise a group delay difference parameter indicating a difference ingroup delays among one or more base stations and the base station. 26.The method of claim 25, further comprising: receiving group delays fromthe one or more base stations over one or more backhaul links, orreceiving a make and model of each of the one or more base stations overthe one or more backhaul links.
 27. The method of claim 26, furthercomprising: calculating the group delay difference parameter based onthe group delays received from the one or more base stations or the makeand model of each of the one or more base stations.
 28. The method ofclaim 25, wherein the one or more base stations comprise one or moreremote radio heads (RRHs) or transmission-reception points (TRPs) of thebase station.
 29. The method of claim 20, wherein the one or more groupdelay parameters further comprise a group delay uncertainty parameterindicating an uncertainty of the group delay of the wireless device. 30.The method of claim 20, wherein the one or more group delay parametersfurther comprise one or more Tx/Rx configurations, each Tx/Rxconfiguration corresponding to a Tx/Rx chain through the wirelessdevice, each Tx/Rx configuration comprising link parameters associatedwith a communication link established between the wireless device andanother network node for determining an RTT there between.
 31. Themethod of claim 30, wherein the link parameters comprise one or more oftransmit/receive beams, antenna panels, transmission power used, andbandwidth.
 32. The method of claim 20, wherein the wireless devicecomprises a user equipment (UE), a base station, a TRP, or an RRH. 33.The method of claim 20, wherein the positioning entity comprises thewireless device, a UE, a base station, a network node, or a locationserver located in a core network or at a base station.
 34. A networknode, comprising: at least one transceiver; at least one memorycomponent; and at least one processor, wherein the at least onetransceiver, the at least one memory component, and the at least oneprocessor are configured to: collect a plurality of round trip times(RTTs) between a user equipment (UE) and a plurality of base stations(BSs), each RTT of the plurality of RTTs associated with a BS of theplurality of BSs, and each RTT representing a total flight time of anRTT signal back and forth between the UE and the associated BS; andperform a differential RTT based positioning procedure to determine aposition of the UE based on differences of the RTTs among the pluralityof RTTs.
 35. The network node of claim 34, wherein the at least onetransceiver, the at least one memory component, and the at least oneprocessor being configured to perform the differential RTT basedpositioning procedure comprises the at least one transceiver, the atleast one memory component, and the at least one processor beingconfigured to: determine a reference BS among the plurality of BSs;determine a differential RTT set from the plurality of RTTs, thedifferential RTT set comprising one or more differential members, eachdifferential member corresponding to a BS other than the reference BS,and each differential member representing a differential distancecalculated based on a difference in the RTT associated with thereference BS and the RTT associated with the BS corresponding to thedifferential member; and determine the position of the UE based on thedifferential RTT set.
 36. The network node of claim 34, wherein the atleast one transceiver, the at least one memory component, and the atleast one processor being configured to collect the plurality of RTTscomprises the at least one transceiver, the at least one memorycomponent, and the at least one processor being configured to receiveone or more RTT reports, the one or more RTT reports comprising theplurality of RTTs.
 37. The network node of claim 36, wherein the atleast one transceiver, the at least one memory component, and the atleast one processor are further configured to: determine whether UEand/or BS group delays are included in the plurality of RTTs, whereinthe differential RTT based positioning procedure is performed when it isdetermined that the UE and/or BS group delays are included in theplurality of RTTs.
 38. The network node of claim 37, wherein the atleast one transceiver, the at least one memory component, and the atleast one processor are further configured to: perform an absolute RTTbased positioning procedure to determine the position of the UE when itis determined that the plurality of RTTs do not include the UE groupdelay and do not include the BS group delays, wherein the at least onetransceiver, the at least one memory component, and the at least oneprocessor being configured to perform the absolute RTT based positioningprocedure comprises the at least one transceiver, the at least onememory component, and the at least one processor being configured to:determine an absolute RTT set based on the plurality of RTTs, theabsolute RTT set comprising one or more absolute members, each absolutemember corresponding to a BS, and each absolute member representing anabsolute distance between the UE and the corresponding BS calculatedbased on the RTT associated with the corresponding BS; and determine theposition of the UE based on the absolute RTT set.
 39. The network nodeof claim 37, wherein the at least one transceiver, the at least onememory component, and the at least one processor are further configuredto: receive one or more group delay parameters from the UE and/or atleast one of the plurality of BSs, wherein the one or more group delayparameters comprise an RTT type parameter indicating whether theplurality of RTTs are measured RTTs or are actual RTTs, and wherein itis determined that the UE and/or the BS group delays are included in theplurality of RTTs when the RTT type parameter indicates that theplurality of RTTs are measured RTTs.
 40. The network node of claim 39,wherein the one or more group delay parameters further comprise a groupdelay difference parameter indicating a difference in the BS groupdelays among the plurality of B Ss, wherein the at least onetransceiver, the at least one memory component, and the at least oneprocessor are further configured to determine whether or not thedifference indicated by the group delay difference parameter is within athreshold difference, and wherein the differential RTT based positioningprocedure is performed when it is determined that the UE and/or BS groupdelays are included in the plurality of RTTs, and when the difference iswithin the threshold difference.
 41. The network node of claim 39,wherein the one or more group delay parameters further comprise a groupdelay uncertainty parameter indicating an uncertainty in the BS groupdelays among the plurality of BSs, wherein the at least one transceiver,the at least one memory component, and the at least one processor arefurther configured to determine whether or not the uncertainty indicatedby the group delay uncertainty parameter is within a thresholduncertainty, and wherein the differential RTT based positioningprocedure is performed when it is determined that the UE and/or BS groupdelays are included in the plurality of RTTs, and when the uncertaintyis within the threshold uncertainty.
 42. The network node of claim 39,wherein the one or more group delay parameters further comprise one ormore Tx/Rx configurations, each Tx/Rx configuration corresponding to aBS, each Tx/Rx configuration comprising link parameters associated witha communication link established between the UE and the corresponding BSfor determining the RTT there between, wherein the at least onetransceiver, the at least one memory component, and the at least oneprocessor are further configured to determine whether or not differencesamong the Tx/Rx configurations are within a threshold Tx/Rxconfiguration difference, and wherein the differential RTT basedpositioning procedure is performed when it is determined that the UEand/or BS group delays are included in the plurality of RTTs, and whenthe configuration differences among the Tx/Rx configurations are withinthe threshold Tx/Rx configuration difference.
 43. The network node ofclaim 42, wherein the link parameters comprise any one or more oftransmit/receive beams, transmission power used, and bandwidth.
 44. Thenetwork node of claim 36, wherein the network node comprises a locationserver.
 45. The network node of claim 44, wherein the one or more RTTreports are received from a reporting BS, the reporting BS being one ofthe plurality of BSs.
 46. The network node of claim 45, wherein the oneor more RTT reports are included in LTE positioning protocol annex(LPPa) signaling and/or in New Radio positioning protocol annex (NR-PPa)signaling from the reporting BS.
 47. The network node of claim 44,wherein the one or more RTT reports are received from the UE.
 48. Thenetwork node of claim 47, wherein the one or more RTT reports areincluded in LTE positioning protocol (LPP) signaling from the UE. 49.The network node of claim 36, wherein the network node comprises the UE.50. The network node of claim 49, wherein the one or more RTT reportsare received from a location server or a reporting BS.
 51. The networknode of claim 36, wherein the network node comprises a reporting BS ofthe plurality of BSs.
 52. The network node of claim 51, wherein the oneor more RTT reports are received from a location server or the UE.
 53. Awireless device, comprising: at least one transceiver; at least onememory component; and at least one processor, wherein the at least onetransceiver, the at least one memory component, and the at least oneprocessor are configured to: provide one or more group delay parametersfor the wireless device to a positioning entity, wherein the one or moregroup delay parameters comprise a round-trip-time (RTT) type parameterindicating whether RTTs reported by the wireless device are measuredRTTs or actual RTTs, and wherein it is determined that a group delay ofthe wireless device is included in the reported RTTs when the RTT typeparameter indicates that the reported RTTs are measured RTTs.
 54. Thewireless device of claim 53, wherein the at least one transceiver, theat least one memory component, and the at least one processor arefurther configured to: perform a measurement of a reference signalreceived from another wireless device.
 55. The wireless device of claim54, wherein the at least one transceiver, the at least one memorycomponent, and the at least one processor are further configured to:provide, to the positioning entity, an indication of which group delayparameter of the one or more group delay parameters applies to themeasurement of the reference signal.
 56. The wireless device of claim53, wherein the at least one transceiver, the at least one memorycomponent, and the at least one processor are further configured to:transmit the one or more group delay parameters to the positioningentity as part of capability information of the wireless device.
 57. Thewireless device of claim 53, wherein the wireless device comprises abase station.
 58. The wireless device of claim 57, wherein the one ormore group delay parameters further comprise a group delay differenceparameter indicating a difference in group delays among one or more basestations and the base station.
 59. The wireless device of claim 58,wherein the at least one transceiver, the at least one memory component,and the at least one processor are further configured to: receive groupdelays from the one or more base stations over one or more backhaullinks, or receive a make and model of each of the one or more basestations over the one or more backhaul links.
 60. The wireless device ofclaim 59, wherein the at least one transceiver, the at least one memorycomponent, and the at least one processor are further configured to:calculate the group delay difference parameter based on the group delaysreceived from the one or more base stations or the make and model ofeach of the one or more base stations.
 61. The wireless device of claim58, wherein the one or more base stations comprise one or more remoteradio heads (RRHs) or transmission-reception points (TRPs) of the basestation.
 62. The wireless device of claim 53, wherein the one or moregroup delay parameters further comprise a group delay uncertaintyparameter indicating an uncertainty of the group delay of the wirelessdevice.
 63. The wireless device of claim 53, wherein the one or moregroup delay parameters further comprise one or more Tx/Rxconfigurations, each Tx/Rx configuration corresponding to a Tx/Rx chainthrough the wireless device, each Tx/Rx configuration comprising linkparameters associated with a communication link established between thewireless device and another network node for determining an RTT therebetween.
 64. The wireless device of claim 63, wherein the linkparameters comprise one or more of transmit/receive beams, antennapanels, transmission power used, and bandwidth.
 65. The wireless deviceof claim 53, wherein the wireless device comprises a user equipment(UE), a base station, a TRP, or an RRH.
 66. The wireless device of claim53, wherein the positioning entity comprises the wireless device, a UE,a base station, a network node, or a location server located in a corenetwork or at a base station.
 67. A network node, comprising: means forcollecting a plurality of round trip times (RTTs) between a userequipment (UE) and a plurality of base stations (BSs), each RTTassociated with a BS of the plurality of BSs, and each RTT of theplurality of RTTs representing a total flight time of an RTT signal backand forth between the UE and the associated BS; and means performing adifferential RTT based positioning procedure to determine a position ofthe UE based on differences of the RTTs among the plurality of RTTs. 68.A wireless device, comprising: means for providing one or more groupdelay parameters for the wireless device to a positioning entity,wherein the one or more group delay parameters comprise around-trip-time (RTT) type parameter indicating whether RTTs reported bythe wireless device are measured RTTs or actual RTTs, and wherein it isdetermined that a group delay of the wireless device is included in thereported RTTs when the RTT type parameter indicates that the reportedRTTs are measured RTTs.
 69. A non-transitory computer-readable mediumstoring computer-executable instructions for a network node, thecomputer-executable instructions comprising: one or more instructionscausing the network node to collect a plurality of round trip times(RTTs) between a user equipment (UE) and a plurality of base stations(BSs), each RTT of the plurality of RTTs associated with a BS of theplurality of BSs, and each RTT representing a total flight time of anRTT signal back and forth between the UE and the associated BS; and oneor more instructions causing the network node to perform a differentialRTT based positioning procedure to determine a position of the UE basedon differences of the RTTs among the plurality of RTTs.
 70. Anon-transitory computer-readable medium storing computer-executableinstructions for a wireless device, the computer-executable instructionscomprising: one or more instructions causing the wireless device toprovide one or more group delay parameters for the wireless device to apositioning entity, wherein the one or more group delay parameterscomprise a round-trip-time (RTT) type parameter indicating whether RTTsreported by the wireless device are measured RTTs or actual RTTs, andwherein it is determined that a group delay of the wireless device isincluded in the reported RTTs when the RTT type parameter indicates thatthe reported RTTs are measured RTTs.